The atomic and ionic radii of transition elements are smaller than those of pblock elements and larger than those of s-block elements. The atomic and ionic radii of first transition elements are given in the table. This table shows the atomic radii of the elements of first transition series. For the element scandium the atomic radius is 144 picometre. For the element Titanium the atomic radius is 132 picometre. For the element Vanadium the atomic radius is 122 picometre. For the element Chromium the atomic radius is 118 picometre. For the element Manganese the atomic radius is 117 picometre. For the element Iron the atomic radius is 117 picometre. For the element cobalt the atomic radius is 116 picometre. For the element Nickel the atomic radius is 115 picometre. For the element Copper the atomic radius is 117 picometre. For the element Zinc the atomic radius is 125 picometre. The atomic radii of the first transition series decreases from Scandium to Chromium and remains almost constant till copper and then increases towards the end. This can be explained based on two effects namely screening and the nuclear charge effect. These two effects oppose each other resulting in increase in nuclear charge. Hence very slight variation in the atomic radii from Chromium to Copper is observed. It has been observed that Zirconium and Hafnium have almost equal atomic radii. This is because of lanthanide contraction.